Table 4 Results of three random-effects meta-analyses on the association between anxiety vs. cannabis use or CUD and anxiety + depression vs. cannabis use

Overall mean weighted OR

OR (95% CI) p _two-tailed

1.24 (1.06-1.45) .006*

1.68 (1.23-2.31) .001*

1.68 (1.17-2.40) .004*

Heterogeneity statistics

Q(df) p _two-tailed I ²

30 (14) .009* 53%

55 (12) <.0001* 78%

8 (4) .091 50%

One-study removed analysis (Additional file 1 : Figure S1)

Which studies, removed one at a time from the analysis, remove the significance of the overall mean weighted OR?

None

None

Cheung et al., 2010 [36]

Cumulative analysis (1993 to 2013) (Additional file 1 : Figure S2)

Which studies, added to all previous studies one at a time, remove the significance of the overall mean weighted OR?

Crum et al., 1993 [38]; Fergusson et al., 1996 [42]

Degenhardt et al., 2001 [39]

NPMS, 2007 [10]

Rosenthal’s Fail-safe N for p > .05

N studies needed to remove the significance of the overall mean weighted OR (N studies missing for every study in meta-analysis needed to remove the significance of the overall mean weighted OR)

N=49 (49/15 = 3)

N=105 (105/13 = 8)

N=17 (17/5 = 3)

Duval and Tweedie’s Trim-and-Fill analysis

Funnel plot symmetrical? N studies missing on either side of the overall mean weighted OR

YES

YES

YES

N=0

N=0

N=0

Begg and Mazumdar Rank Order Correlation

τ

.13

-.19

-.30

p _two-tailed

.488

.360

.462

Egger’s regression

intercept

.25

1.73

−4.05

p _two-tailed

.748

.005*

.415